Process for the development of photographic material

ABSTRACT

A METHOD OF DEVELOPING EXPOSED PHOTOGRAPHIC SILVER HALIDE ELEMENTS IS DESCRIBED ACCORDING TO WHICH AN AQUEOUS ALKALINE COMPOSITION IS USED IN THE PRESENCE OF AN ANIONIC SILVER HALIDE DEVELOPING AGENT AND A DIQUATERNARY CYCLIC AMMONIUM SALT WHICH BY THE UPTAKE OF 1 ELECTRON FORMS STABLE WEITZ RADICALS. THE DIQUATERNARY CYCLIC AMMONIUM SALTS ACCELERATE DEVELOPMENT AND THE DEVELOPMENT ACCELERATING EFFECT SURPASSES THAT OF RELATED QUATERNNARY AMMONIUM COMPOUNDS THAT DO NOT FORM STABLE WEITZ RADICALS.

United States Patent 3,713,827 PROCESS FOR THE DEVELOPMENT OFPHOTOGRAPH'IC MATERIAL Jozef Frans Willems, Wilrijk, Belgium, assignorto Gcvaert-Agfa N.V., Mortsel, Belgium No Drawing. Filed Oct. 7, 197.0,Ser. No. 78,937 Claims priority, application Great Britain, Oct. 27,1969, 52,569/ 69 Int. Cl. G03c 5/30 US. Cl. 96-663 7 Claims ABSTRACT OFTHE DISCLOSURE A method of developing exposed photographic silver halideelements is described according to which an aqueous alkaline compositionis used in the presence of an anionic silver halide developing agent anda diquaternary cyclic ammonium salt which by the uptake of 1 electronforms stable Weitz radicals. The diquaternary cyclic ammonium saltsaccelerate development and the development accelerating efiect surpassesthat of related quaternary ammonium compounds that do not torm stableWeitz radicals.

This invention relates to the development of photographic materialscontaining exposed silver halide in the presence of substancesinfluencing the development.

It is known that certain chemical compounds such as1-aryl-3-pyrazolidinone compounds, p-phenylenediamine derivatives andp-aminophenol derivatives which used alone are poor developers forphotographic silver halide emulsions, become much more efl'ective whenused in conjunction with other developers such as hydroquinone,hydroquinone derivatives, ascorbic acid, etc. the efi'ect being known assuperadditivity. Though the compounds used in practice are effectivesuperadditive developers, they still present a number of difliculties.For instance, some compounds such as 1-phenyl-3-pyrazolidinone, which iswidely used as superadditive developing agent in conjunction withhydroquinone, is subject to hydrolysis in alkaline medium whereas othercompounds, when used in concentrated aqueous solutions that should bediluted before use, have insuflicient solubility.

It is further known that onium compounds such as quaternary ammonium,quaternary phosphonium and ternary sulphonium compounds are able toaccelerate photographic development by agents which act as doubly ormore highly charged negative ions for instance hydroquinone,hydroquinone derivatives, ascorbic acid, etc., whether as an additive tothe developer or to the emulsion. However, the development acceleratingeifect of the onium compound is lower than that of the abovesuperadditive developing agents.

In accordance with the present invention a new class of developmentaccelerators of the quaternary ammonium type with specific redoxproperties is provided, which a not subject to hydrolysis in alkalinemedium, have a high water-solubility and are very effective acceleratorsof photographic development by doubly or more highly charged negativedeveloper ions as well as by the singly ionized developer anions ofhydroxylamine and derivatives thereof.

Patented Jan. 30, 1973 The novel accelerators of photographicdevelopment by negatively charged developing agents, of use inaccordance with the present invention, are characterized as beingdiquaternary cyclic ammonium compounds which by the uptake of 1 electronform stable Weitz-radicals.

Particularly suitable development accelerators according to the presentinvention are the diquaternary dipyridinium, dithiazolium anddiimidazolium salts and the diquaternary pyridiniumthiazolium andpyridinium-imidazolium salts represented by the following generalformula:

each of Z and Z (the same or different) stands for the atoms necessaryto complete a pyridinium, thiazolium or imidazolium nucleus optionallycarrying fused on aryl nuclei such as benzthiazolium, benzimidazoliumand quinolinium and further substituents such as alkyl and aryl A standsfor a chemical bond linking the 2-position 0f Z =pyridinium, thiazoliumor imidazolium to the 2- position of Z =pyridinium, thiazolium orimidazolium or to the 4-position of Z =pyridinium or for a chemical bondlinking the 4- position of Z =Z =pyridinium, each of R and R stands foralkyl including substituted alkyl or R together with R may stand forethylene including substituted ethylene when A is a chemical bondlinking the 2-position of Z to the 2-position of Z2, and X'- stands foran anion or acid radical for example halide, p-toluene sulphonate, alkylsulphate or perchlorate.

1 1.. Hz Q PREPARATION l: COMPOUND 3 21.2 g. (0.1 mole) of2-(4-pyridyl)benzothiazole and 250 g. (2 moles) of dimethylsulphate areheated for 5 hours at 1 C. on an oil bath. The precipitate formed uponcooling is filtered by suction and washed with diethyl ether. Yield: 40g. Melting point: 190 C.

PREPARATION 2: COMPOUND 4 5 g. (0.025 mole) of 1,10-phenanthrolinemonohydrate and 20 ml. of dibromoethane are refluxed for 1 hourwhereupon the precipitate formed is recrystallized from ethanol/water.Yield: 3 g. Melting point: 260 C.

PREPARATION .3 COMPOUND 5 6.8 g. (0.025 mole) ofl-pheny1-2-(2-pyridyl)benzimidazole and 20 ml. of dibromoethane arerefluxed for 1 hour whereupon the precipitate formed is recrystallizedfrom ethanol. Yield: 5 g. Melting point: 260 C.

PREPARATION '4: COMPOUND 6 10.6 g. (0.05 mole) of2-(2-pyridyl)benzthiazole and 9.4 g. (0.05 mole) of dibromoethane areheated for 48 hours at 130 C. in a sealed tube whereupon the residue isboiled with acetone. Yield: 4 g. Melting point: 260 C.

Thus, in accordance with the present invention there is provided aprocess of making photographic records which comprises treating aphotographic material having layers containing developable silver saltswith an aqueous alkaline solution in the presence of a negativelycharged developing agent and a diquaternary salt as described above. Theinvention also includes developer compositions comprising in addition toa negatively charged developing agent, a diquaternary salt as described.

The diquaternary salts of use according to the present invention may beadded to the developing bath or to the emulsion or to bothsimultaneously, the developing bath being preferred however.

The accelerating eifect of the compounds according to the invention isnot restricted to certain types of negatively charged developing agents.It is apparent with all developing agents the ionized forms of which inalkaline medium carry one or more negative charges. These developingagents including among others hydroquinone, hydroquinone derivatives,ascorbic acid, sodium dithionite addition products of sodium dithioniteand formaldehyde, as Well as hydroxylamine and hydroxylarninederivatives.

The use of hydroxylamine and derivatives as developing agents has beendisclosed among others in U.S. Pat. 2,857,276. The oxidation products ofthese hydroxylamine developing agents have the favourable property ofleaving no residual stain in the silver image obtained. Hydroxylamineitself is less suitable for use as developing agent because it can giverise to fog but the N,N-dialkylhydroxylamines such asN,N-diethylhydroxylamine and the heterocyclic N-hydroxylamines such asN-hydroxymorpholine, N-hydroxypiperidine and N-hydroxypyrrolidinedisclosed in the above U.S. patent are particularly suitable. Otherhydroxylamine derivatives that have been proposed for use as silverhalide developing agents and of which the development activity is higherthan that of the N,N-dialkyl hydroxylamines include for exampleaminoalkyl hydroxylamines, more especially N,N-dialkylhydroxylamineshaving in at least one of the N-alkyl groups an intralinear aminonitrogen atom, either cyclic or acyclic, examples of which can be foundin U.S. Pat. 3,287,125, alkoxyhydroxylamines, more especiallyN,N-dialkylhydroxylamines of which at least one of the N-alkyl groups issubstituted by alkoxy or alkoxyalkoxy, examples of which can be found inU.S. Pat. 3,293,034, and sulphone hydroxylamines, more especiallyN,N-dialkylhydroxylamines having in at least one of the N-alkyl groupsan intralinear sulphonyl SO group, examples of which can be found-inU.S. Pat. 3,287,124.

The developing bath may comprise in addition to the anionic developingagent any of the common ingredients employed in developing compositions,e.g., alkalies such as sodium hydroxide, potassium hydroxide, sodiumcarbonate, trisodium phosphate etc., silver halide solvents such assodium thiosulphate, sodium thiocyanate and cyclic imides such asbarbiturates or uracils, preservatives such as sulphites, bisulphites,metabisulphites and acids such as boric acid and citric acid. Furtherthe developer composition may comprise potassium bromide andwatersoftening agents such as polyphosphates and derivatives of ethylenediamine tetraacetic acid, antifoggants such as benzotriazole,S-nitro-benzotriazole and 6-nitrobenzimidazole, wetting agents,developing agents having a superadditive elfect with the anionicdeveloping agent used, e.g., 1-phenyl-3-pyrazolidinone as well as othercompounds known in the photographic development technique.

The pH of the baths may vary within wide limits and depends on the kindof developing agent involved and the desired etfect. For instance, inthe case of hydroquinone and ascorbic acid the compounds of useaccording to the present invention have little effect below pH 9 whereasin the case of sodium dithionite the pH may be lower, e.g., pH 8. Theoptimum pH-value for any developing agent used, can best be determinedby some simple tests determining the pH-dependency of the developmentaccelerating eflect. In general the pH is comprised between pH -8 and pH13.

The amount of cyclic diquaternary ammonium compound used according tothe present invention depends on the very compound, on the nature of thecolloid binder of the silver halide grains and on the amount and type ofsilver halide in the emulsion.

The amount of onium compound incorporated into the developing bath canvary between very wide limits and depends on the developing agent used.The optimum concentration for any diquaternary salt of use according tothe invention can best be determined by employing a series ofconcentrations in several batches of the same developer and determiningthe speed obtained before and after incorporation of the said compoundin the usual manner which is of course well known to those skilled inthe art. Generally, the onium compound is used in amounts rangingbetween 0.01 mmole and 20 mmole per litre.

The development acceleration obtained with the products according to thepresent invention can be combined With a chemical sensitization by meansof chemical sensitizing agents such as sulphur-containing compounds,e.g, allyl isothiocyanate, allyl thiourea, or sodium thiosulphate,reducing agents such as the tin compounds described in the Belgianpatent specifications 493,464 filed Jan. 24, 1950 and 568,687 filed June18, 1958 both by Gevaert Photo-Producten N.V., the iminoaminomethanesulphonic acid compounds described in the British patent specification789,823, filed .Apr. 29, 1955 by Gevaert Photo-Producten N.V., orprecious metal compounds such as gold, platinum, palladium, iridium,ruthenium and rhodium compounds.

The products influencing the development according to the presentinvention can also be used in combination with stabilizing agents forsilver halide emulsions, such as mercury compounds and the compoundsdescribed in the Belgian patent specifications 571,916 and 571,917 bothfiled Oct. 10, 1958 by Gevaert Photo-[Producten N.V., and in combinationwith sensitizing and stabilizing cadmium salts in the light-sensitivematerial as well as in the developer.

They may further be used in combination with alkylene oxide polymers andcondensation products of alkylene oxide. The alkylene oxide compoundsmay be of various types and include, e.g., those described in the US.patent specifications 1,970,578 by Conrad Schoeller and Max Wittwerissued Aug. 21, 1934, 2,240,472 by Donald -R. Swan issued Apr. 29, 1941,2,423,549 by Ralph K. Blake, William A. Stanton, Ferdinant Schulzeissued July 8, 1947, 2,441,389 by Ralph K. Blake issued May 11, 1948,2,531,832 by William A. Stanton issued Nov. 28, 1950, 2,533,990 by RalphK. Blake issued Dec. 12, 1950 and the British patent specifications920,637 filed May 7, 1959 by Gevaert Photo-Producten N.V., 940,051 filedNov. 1, 1961 by Gevaert Photo-Producten N.V., 945,340 filed Oct. 23,1961 by Gevaert Photo-Producten N.V., 991,608 filed June 14, 1961 byKodak and the Belgian patent specification 648,710 filed June 2, 1964 byGevaert Photo-Froducten NV.

The development accelerators of the invention may be used inconventional or wet development of silver halide emulsions, in diffusiontransfer processes, both dye and silver, in such photographic processesknown as stabilization processing wherein it is desired to eliminate orminimize the need for Washing or stabilizing operations in liquid bathssubsequent to the formation of the silver print, etc.

In diffusion transfer processes, as is well known in the silver saltwhich is transferred to the image-receiving material and there reducedto silver to form a positive print. The processing composition normallyincludes a silver halide solvent, such as sodium thiosulphate, sodiumthiocyanate and cyclic imides such as barbiturates or uracils, whichforms with silver halide a soluble complex as is well known in the artof forming silver images by transfer, and may also include afilm-forming material such as sodium carboxymethyl cellulose orhydroxyethyl cellulose, starch or gum for increasing the viscosity ofthe composition as, for instance, in the case of in-camera silvercomplex diffusion transfer processing. As is known in the art ofdiffusion transfer processing the developing agents may be present inthe processing solution and/ or the light-sensitive material and/or theimage-receiving material.

In stabilization processing the time-consuming fixing and washingoperations are eliminated in order to produce the photographic record inthe least possible time, by converting after development, with the aidof stabilizing agents such as ammonium thiocyanate, the unexposed andundeveloped silver halide of the photographic emulsion into colourlesslight-intensitive compounds that need not be removed by washing.

The following examples illustrate the present invention.

EXAMPLE 1 G. Sodium carbonate 20 Sodium hexametaphosphate 1 Sodiumsulphite (anhydrous) 20 Potassium bromide 0.5 Hydroquinone 4.4

Water to make 1 litre (pH 10.4).

Other strips are developed in baths having the same composition as bathA but containing in addition thereto 0.31 mmole of1,l'-tetramethylene-bis(pyridinium chloride) and 0.31 mmole of dodecylpyridinium chloride respectively whereas the remaining strips aredeveloped in baths having the same composition as bath A but containingin addition, as listed in Table I, 0.31 millimole of a diquaternary saltaccording to the above general formula. The densities are determinedafter a developing time of 10 sec., 20 sec., 30 sec., 1 min., 2 min. and5 min. and are listed in the following table.

Density after a development time of- Developing bath 10 sec. 20 sec. 30see. 1 min. 2 min. 5 min.

Bath A 0. 04 0. 04 0. 04 0. 04 0. 06 0. 80 Bath A plus 0.31 111111016 of1, 1-tetramethylene-bis (pyridinium chloride) 0. 04: 0. 04 0. 09 0.64 1. l3 2. 79 Bath A plus 0.31 mmole of dodecyl pyridinimn chloride 0-04 0. 04 04 0. 0? Bath A plus 0.31 mmole of compound 1 0. (157 1. 91 3Bath A plus 0.31 mmole of compound 2.. 0: 0 o: 31 0' 49 1 07 1 86 3 BathA plus 0.31 mmole of compound 3-.

1 In this bath comprising a diquaternary ammonium bromide the amount ofpotassium bromide has been reduced to 463 mg. 5

ative results.

the unexposed silver halide is converted into a complex as to obtaincompar- Weitz-radicals.

7 EXAMPLE 2 8 EXAMPLE 4 Strips of a photographic material comprising alightsensitive silver halide emulsion layer coated on a cellulosetriacetate support, are exposed through a grey filter with a Densityafter a development time oi- Developing bath sec. sec. 30 see. 1 min. 2min. 5 min.

Bath A 0. 04 0. 04 0. 05 0. 05 0. 06 0. 80 Beth A plus L55 mmole of l,l-tetramethylene-bis (pyridinium chloride). 0.04 0. 04 0. l7 0. 66 1.21 1. 71 Bath A plus 6.2 mmole of 1, 1-tetramethylene-bis (pyridiniumchloride). 0. 07 0.33 0. 55 0. 93 1. 34 1. 64 Bath A plus 1.55 mmole ofcompound 1 1 0.21 0. 54 0. 87 1. 49 2. 71 3 Beth A plus 6.2 mmole ofcompound 1 2 0. 33 O. 71 1. 01 1. 76 3 8 1 In this bath containing adiquaternary ammonium bromide, the amount of potassium bromide has beenreduced to 316 mg. in order to obtain comparative results.

2 In order to obtain comparative results no potassium bromide has beenadded to this bath.

These density values confirm the results attained in Example 1.

EXAMPLE 3 Strips of a photographic material comprising a lightsensitivesilver halide emulsion layer, coated on a cellulose triacetate support,are exposed through a grey filter with a light-quantity (E) whichcorresponds to the shoulder part of the density/ log E curve. G. Forcomparison purposes some of these film strips are Sodiumhexamctaphosphate 1 developed at 20 C. in separate developing baths,having S dium Carbonate 20 different pH values and having the followingcompositions. Trisodi'urn phosphate 20 Sodium hydroxide 2.7 BathPotassium bromide 0.5 A B C D Ascorbic acid 7 Water to make 1 litre (pH12). Sodium hexametaphosphate, grams 1 1 1 1 gogium sulphkite(tanhydrous), grams 12g 20 20 20 0 rum me a 0T8 e, I'SIIIS l fcarbonate, grgams 20 20 Another strip is developed in a bath having thesame y quinone, grams 4.4 4 4 4.4 4.4 com Trisodmm phosDhatemms M 20 4oplosltlon h E b ntaining n addltlon 9.05 lsjogimp hygoxiqg, grams n n 23 e f ,1 m hylen 1s(pyrl lmum chlorlde) 0 assium romi e, grams 7 watertomake, me 2 1 E 1 1 W fleas stlll th strlp is v l p d in a bath hav ngthe same composition as bath E but containing in addition gg 8%: 0.05mmole of Compound 1. The densities are determined after a developmenttime of 10 sec., 20 sec., 30 sec., 1 min.

P and 2 min. and are listed in the following table.

Density after a development time of- Developing bath 10 sec. 20 see. 30sec. 1 min. 2 min.

Bath E Bath E plus 0.05 mmole of 1,1-tetramethylene-bis(pyridiniumchloride) Bath E plus 0.05 mole of compound 1 1 0.10 0.18 0: 27 0170 1:10

1 In this bath comprising a diquaternary ammonium bromide the amount ofpotassium bromide was reduced to 494 mg. so as to obtain comparativeresults.

Other film strips are developed in baths A, B, C and D having the samecomposition as the above baths but comprising in addition 6.2 mmole ofCompound 1. In these baths A, B, C and D comprising a diquaternaryammonium bromide no potassium bromide was added so as to obtaincomparative results.

The following density values were attained.

Densities obtained after a development time of- Developing bath 1 min. 2min. 4 min. 8 min. 16 min.

From these results appears clearly that Compound 1 has a markedly higheraccelerating effect on development by ascorbic acid than the related1,1-tetramethylene-bis (pyridinium chloride).

EXAMPLE 5 different pH values and having the following compositions:

Sodium hydroxide, grams" Potassium bromide, grams. Ascorbic acid, grams1 7 sh p 10 From the results obtained it appears that Compound 1 has ahigh development accelerating efiect whereas the related1,l-tetramethylene-bis(pyridinium chloride) inhibits development.

5 EXAMPLE 7 This example is analogous to Example 6 with the differencehowever that the developing bath now contains as developing agentinstead of 4.2 g. of hydroxylamine 10 hydrochloride 5 g. ofN-methylhydroxylamine hydro- 1 chloride (bath I). 2 P The resultsattained are listed in the following table.

Densities obtained after a development time of- Developing bath sec. 20sec. 1 min. 3 min. min.

Bath I." 0. 04 0. 05 0. 07 O. 60 1 09 Bath I plus 0.5 g. (1.75 mole) of1,1-tetramethy1ene-b 0. 04 O. 04 0.05 0.32 0. 91 Bath I plus 0.5 g.(1.38 mmole) of compound 1. 0- 04 0. l3 0. 65 2. 28 3 Other film stripsare developed in baths having the same composition as the above bathsbut comprising in addition 1.55 mmole of Compounds 1 and 2.

The density values obtained are listed in the following table.

From these results too it appears that 1,1-tetramethylene-bis(pyridiniumchloride) inhibits development whereas Compound 1 has a favourabledevelopment accelerating effect.

Densities obtained after a development time of Developing bath 10 sec.sec. see. 1 min. 2 min. 5 min.

Bath F 0. 04 0. 04 0. 04 0. 04 Bath F plus 1.55 mmole of compound 1 1 0.04 0. 06 0. 13 0. 44 Bath F plus 1.55 mmole of compound 2 0. 04 0. 04 0.06 0. 80 Bath G 0.04 0. 04 0.04 0.05 Bath G plus 1.55 mmole of compound1 l 0. 72 0. 86 1. 22 1. 72 Bath G plus 1.55 mmole of compound 2 0.28 0.0. 78 1. 04

1 In these baths comprising a diquaternary ammonium bromide the amountof potassium bromide was reduced to 316 mg. so as to obtain comparativeresults.

EXAMPLE 6 ,After exposure of film strips as described in Example 1, eachof the film strips is developed at 20 C. in separate developing baths.One of them is developed in a bath H EXAMPLE 8 Densities obtained aftera development time of- Developing bath 0 sec. 20 sec. 1 min. 3 min. 5min.

Bath .1 0.04 0.04 0.04 0.07 0.37 Bath .1 plus 88 mg. (0.31 mmole) of1,1'-tetramethylene-bis-(pyridinium chloride)- 0. 04 0. 04 0. 04 0.22 1. 14 Bath .7 plus 500 mg. (1.75 mole) of1,1-tetramethylene-bis-(pyrrd1mum chloride) 0. 04 0. 04 0.05 0. 43 1. 77Bath J plus 112 mg. (0.31 mole; of compound 1 0. 04 0. 04 0. 07 1. 14 2.96 Bath J plus 500 mg. (1.38 mmole of compound 1 0. 04 0.05 0. 27 2. 123 containing as developing agent hydroxylamine hydrochloride and havingthe following composition:

Water to make 1 litre.

Other strips are developed in baths having the same composition as bathH but containing in addition one of the compounds identified in thetable below.

The densities obtained after various development times are listed in thefollowing table.

By these results it is shown that Compound 1 has a markedly highereffect on development of diethylhydroxylamine than1,1'-tetramethylene-bis(pyridinium chloride).

EXAMPLE 9 After exposure of film strips as described in Example 1, eachof the film strips is developed at 20 C. in separate developing baths.One of them is developed in a bath K containing as developing agentRongal HT Type 66 (trade name of Badische Anilin & Soda FabrikLudwigshafen, Germany, for an addition product of formal- Densitiesobtained aiter a development time of- Developing bath 0 see. 20 S90. 1min. 3 min. 5 min.

Bath H 0. 04 0. 05 0. 34 0. 1. 43 Bath H plus 0.5 g. (1.75 mmole) ofl,1-tetramethylene-bis-(pyiidinium chloride) 0. 04 0. 04-. 0. 25 0.79 1. 03 Bath H plus 0.5 g. (1.38 mmole) of compound 1. 0- 0 09 62 1- 552. 11

dehyde and sodium dithionite) and having the following composition:

I wherein:

each of Z and Z (the same or diflierent) stands for Boric acid g 20 theatoms necessary to complete a pyridinium, thia- Borax g 25 zolium orimidazolium nucleus which may be sub- Rongal HT Type 66 (trade name) g10 5 situated and carry fused-on aryl nuclei, Potassium iodide mg 20 Astands for a chemical bond linking the 2-position of Sodium bisulphite0.5 g. (pH 8.5) Z =pyridinium, thiazolium or imidazolium to the Water tomake 1 litre. the 2-position of Other strips are developed in bathshaving the same 2=P WP thlazohum or lmldazohum or to composition as bathK but containing in addition 0.05 the PP of mmole of one of thecompounds identified in the table 2=PY for chemlc'al llnkmg the below.4-pos1t1ons of The densities obtained after a development time of 30 1=2=PY sec., 1 min, 3 min., and 5 min. are listed in the followeach of 1and 2 Stands for an alkyl group 1 ing table. 15 gether with R may standfor an ethylene group when Densities obtained after a development timeof- Developing bath sec. 1min. 3min. 5min.

Bath K 0.04. 0.07 0.30 0.70 Bath K plus 0.05 mmole of compound 1 0.63 1.21 2. 02 2. 45 Bath K plus 0.05 mmole of 1,1'-tetramethylene-bis(pyrldinium chloride) 0. O4 0. l0 0. 75 1. 15

These results show that Compound 1 has a higher ac- A is a chemical bondlinking the 2-position of Z to celerating effect on development bysodium dithionite the 2-position of Z and than1,1-tetramethylene-bis(pyridinium chloride). X- stands for an anion oracid radical.

EXAMPLE 10 2. Photographic developingmethod acordmg to clalm 0 1,wherein said development is carried out using as de- A photosensitiveelement was prepared comprising on a paper support a silver bromoiodideemulsion layer containing per kg. an amount of silver halidecorresponding to 60 g. of siliver nitrate.

After exposure, the photosensitive element and an image-receivingelement, which comprises a silver receptive layer containing developmentnuclei dispersed in a matrix of colloidal silica coated on awater-impervious support according to the practice described in U.S.Pat. 2,823,122, were advanced in superposed relationship between a pairof pressure-applying rollers to spread between them in a thin layer thefollowing processing composition:

After a contact period of 36 seconds, the emulsion together with thelayer of processing liquid was stripped from the image-receiving elementto uncover the positive print.

When using a same developing composition but comprising no Compound 1the density of the positive print obtained was markedly lower. Moreover,in the presence of compounds better quality transfer images are obtainedat lower illumination levels as is the case when usingN,N-diethylhydroxylamine alone.

I claim:

1. Photographic developing method which comprises developing an exposedsilver halide emulsion layer of a photographic material with an aqueousalkaline composition in the presence of an anionic developing agentand adiquaternary cyclic ammonium salt, wherein said ammonium saltcorresponds to the formula:

veloping agent a member selected from the group consisting ofhydroquinone, derivatives, ascorbic acid, sodium dithionite,hydroxylamine and hydroxylamine derivatives.

3. Photographic developing method according to claim 1, wherein the saiddiquaternary salt is present in the developing bath in an amount.comprised between 0.01 mmole and 20 mmole per litre.

4. Photographic developing method according to claim 1 wherein saidmethod is used for making images according to the, silver complexdiffusion transfer process.

5. Photographic developing composition for developing an exposed silverhalide emulsion layer of a photographic material comprising in aqueousalkaline solution in addition to an anionic developing agent adiquaternary cyclic ammonium compound corresponding to the formula inclaim 1.

6. Photographic developing composition according to claim 5 containingper litre from 0.01 mmole to 20 mmole of the said diquaternary ammoniumsalt.

7. Photographic developing composition according to claim 6 wherein theanionic developing agent is a member selected from the group consistingof hydroquinone, a hydroquinone derivative, ascorbic acid, sodiumdithionite,, hydroxylarnine and a hydroxylamine derivative.

References Cited UNITED STATES PATENTS 3,240,810 3/1966 Blout ct a1.9666 3,241,963 3/1966 Green et al. 96-66 3,253,915 5/1966 Weyerts et a1.9666 J. TRAVIS BROWN, Primary Examiner E. C. KIMLIN, Assistant ExaminerU.S. Cl. X.R. 9666,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3,713, 827

DATED January 30, 1973 INVENTOR(S) I Jozef Frans WILLEMS It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, line 30, "position" should read positions Column 2, lines 5557, formula 2 should appear as follows:

Column 3, lines 20 29, formula 6 should appear as follows:

Column 10, line 67, "Germany" should read W. -Germany Column 12, lines 4and 5, claim 1, "subsituated" should read substituted Column 12, line 8,delete "the"; Column 12, line 32, claim 2, before "derivatives" inserthydroquinone Signed and Sealed this sixteenth Day of March 1976 [SEAL]RUTH C. MRSON C. MARSHALL DANN Attesnng Officer Commissioner oj'Patentsand Trademarks

